Brassieres are worn not only to provide support for women's breasts, but also to enhance the shape of the breasts within the brassieres, to enhance the shape of the portion and amount of the breasts above the brassieres and to modify the cleavage between the breasts.
Push-up bras are designed to shape and elevate the breasts. Push-up bras usually contain a rubber pad received in a pocket in the lower front panels of the bra cups. The pad is formed by molding into a complex arcuate shape. Rubber pads are both stiff and uncomfortable and do not exhibit the natural feel of breast tissue. Rubber pads also cause insecurity due to straying of the pads. Other push-up bras used a more yielding silicone foam and some use Nylon (polyamide) padding to shape and lift.
Push-up bras with liquid filled envelopes have recently appeared on the market. These pads more clearly emulate the consistency of breast tissue. However, the liquids used to fill the envelopes are not satisfactory. Silicone oil liquids are very expensive and are hard to seal. Hydrocarbon oils have also been utilized as the liquid either alone or in a mixture with water. Hydrocarbons can attack the envelope. The liquids in the envelope are heated to body temperature of about 99.degree. F. At this temperature, evaporation is increased and the hydrocarbon vapors can permeate through the wall of the envelope, creating offensive, unpleasant odors. Furthermore, water vapor is also able to permeate through the wall of the envelope decreasing the liquid volume in the envelope. The envelope could rupture on impact or when pierced by a sharp object causing embarrassment, discomfort and destruction of the pad.
List of References Patentee U.S. Pat. No. Block, et al. 3,620,222 Kirby, et al. 3,845,507 Lynch 3,986,123 Miller 5,235,974